Letoff mechanism for looms



Nov. 28, 1944. w. Y. ROBB LET-OFF MECHANISM FOR LOOMS Filed April 12,1943 3 Sheets-Sheet l flNvEN'roR WALTERY ROBE ATTORNEY Nov. 28, 1944. w.Y. ROBB LET-OFF MECHANISM FOR LOOMS Filed April 12, 1943 5 Sheets-Sheet2 .2 @w @WW QMAR L R o n 3j 5 A .2 a o R N hm; T 5 N Y R 9: Q m. E m 0RE MH m m n Ai H Y 12 I M A Nov. 28, 1944. w. Y. ROBB LET-OFF MECHANISMFOR LOOMS Filed April 12, 1943 s Sheets-Sheet s l NvE'NTo R WALTER Y;Rose ATTO RNEY Patented Nov. 28; 1944 UNITED 'STATES PATENT OFFICE2,863,996 Ls'rorr MECHANISM roa LOOMS Walter Y. Robb, Whitlnsv-lllc,Mass, assignor to Crompton & Knowles Loom Works, Worcester, Mass, acorporation of Massachusetts Application April 12, 194:, Serial No.482,683 9 Claims. (of. 139-352) .more beams all of which turn to feedtheir respective sheets of warps. When looms of this type areof-considerable width such as 20/4, it is difllcult to use beams tosupply warp for the full width of the fabric and I overcome thisdifllculty by aligning two or more warp beams to supply a group ofsheets of warp threads. Each beam has its own let-ofi' mechanism whichoperates independently of other similar mechanisms and because of thisfact there is a possibility that one of the beams may fail to let off asmuch warp as the other beam which is aligned with it.

The warp threads of each sheet pass over a whip roll the position ofwhich is determined in P t by the warp tension and it is a moreimportant object of my present invention to Drovide means for stoppingthe loom if the warp tension in any sheet increases sufficiently to movethe corresponding whip roll to an abnormal position. I

It is another object of my present invention to provide each of the warpsystems with a loom controlling electric switch in position to beoperated by the associated whip roll when the latter moves to abnormalposition for the purpose of eflecting loom stopp ge before'the warptension becomes high enough to cause thread breakage or distortion ofthe fabric.

.With these and other objects in view which will appear as thedescription proceeds, my invention resides in the combination andarrangement of parts hereinafter described and set forth.

In the accompanying drawings, wherein a convenient embodiment of myinvention is set forth,

Fig. l is a side elevation of part of an Axminster loom having myinvention applied thereto,

Fig. 2 is an enlargement of part of Fig. 1 showing the whip rolls andthe let-off mechanism for one beam, Y

Fig. 3.is a plan view of Fig. 2 looking in the direction of arrow 3,

Fig. 4 is a detailed front elevation in the direction of arrow 4, Fig..2 showing the electric switch and its operating mechanism on anenlarged scale,

Fig. 5 is a detail vertical section on line [-5 of Fig. 2,

Fig. 6 is a plan view of the loom looking in the direction of arrow 6,Fig. 1,

Fig. 7 is a detail side elevation locking in the directionof arrow 1,Fig. 6 showing the weights for the whip rolls, and

Fig. 8 is a diagrammatic view of the electric circuit and loom shippercontrol mechanism used with my invention.

Referring particularly to Figs. 1 and 6 I have shown the lower part ofan Axminster loom frame in and a shaft l I appropriately driven by amotor M indicated in Fig. 8 which causes the shaft to have a rotationevery third pick or beat of the loom for the weaving of so-calledthree-shot Axminster. Mounted on each end of shaft II is a cam 12 havinga groove I3 and a face It. The

a pinion 20 which meshes with a gear 2| secured to the take-up roll 22mounted as at 23 for rotation in the front part of the loom. A hold pawl24 prevents retrograde movement of the ratchet wheel on theidle ornon-working stroke of the pawl I'L- i As will be understood from Fig. la comple rotationof shaft II will cause three rockings of lever IS in acounterclockwise direction to advance the take-up roll 22 by threesuccessive steps, one step for each beat of the loom. The lay L has aforward motion for each beat and the weft needle N is inserted throughthe warp shed once for each beat.

The fabric F extends forwardly from its fell and over the cloth board 25down to and around a guide roll 25 and then up to the take-up roll,

from which point it goes to a wind-up cloth roll not shown. The fabriciscomposed of shots of filling laid by the needle N and warp threadsdesignated generally at W in Fig. 1 which form the sheds for the needle.These warp threads extend through harness mechanism H and thenrearwardly to the warp beams.

The loom set forth herein is used more particularly for the weaving ofheavy fabrics requiring a large number of warp threads and the latterare derived from warp beams located at the back part of the loom asshown in Fig. 6, and considering the left hand part of the loom asviewed in Fig. 6 as its front, I show three pairs of aligned beams, theright hand beams being designated RI, R2 and R3, respectively, whiletheir corresponding left hand beams are indicated at Ll, L2 and L3.

The beams are thus arranged in pairs. each right hand beam aligning withits corresponding left beam.

- frame 33 accommodates the inner ends of the shafts 30. The beams arepreferably all of the same size and will be wound with the same kind ofwarp and for all practical purposes are identical with each other. Eachbeam is rotatable independently of all the other beams and the rate ofits rotation is independent of the rate of rotation of the remainingbeams.

Each beam has its own let-off mechanism which in the present instance ispositive and includes means for turning the beam gradually during loomoperation so that its warp will be unwound. As shown in Fig. 6 thelet-01f mechanism which effects feeding of the warp for beams RI, R2 andR3 are designated generally at Fl. F2 and F3, respectively, and insimilar manner, the let-oil. mechanisms for the left hand beams Ll, L2and L3 are designated generally at F4, F3 and F6, respectively. Sincethese let-oil mechanisms are substantially the same only one of themwill be described.

The shaft of each warp beam has secured thereto a worm wheel 33 whichmeshes with a worm 36 secured to a vertical shaft 31 the lower end ofwhich turns in and is supported by a bearing 38 fastened to the adjacentpart of the loom frame. A second bearing 33 also fastened to the loomframe affords support and bearing for the upper part of the shaft 31, asshown in Figs. 2 and 3.

'Secured to each shaft 31 is a ratchet wheel. actuated by a pawl llpivoted at 42 on an arm 43 having a bearing 43 which is loose on theshaft 31 and free to rock back and forth thereon. A spring 43 carried bythe arm 43 tends to turn the pawl into operative position with respectto the ratchet wheel 40 but permits the pawl to be moved to non-drivingposition relatively to the ratchet. v

The pawls of the several let-oil's are'operated in unison by means ofjointed rods, those pawls at the right of the loom have their arms 43pivotally connected as at 48 to a rod 49 which extends forwardly to anupright lever 50 pivoted as at about a fixed axis. Lever 50 carries aroll 52 located in the groove l3 of the right hand cam I2 which causesforward movement of lever 50, or movement to the left as viewed in Fig.1, three times for each complete rotation of the shaft II. It will thusbe seen that the pawls for the let-offs Fl F2 and F3 all have feedingstrokes in unison and these strokes occur each beat of the loom.

The let-oil's F4, F3 and F6 at the left side of the loom are operated bymechanism similar to that already described and including a rod 53similar to rod 49 extending forwardly to a lever 53 similar to lever 50.The left hand let-offs are therefore also operated in unison andpreferably though not necessarily synchronous with the right handlet-offs.

Provision is made for interrupting the feeding of each of the ratchetwheels 40 by its ratchet for one or more beats of the loom to preventtuming of the associated warp beam should the corresponding sheet ofwarp be too slack. Accordinsly. each shaft 31 has loosely mountedthereon a shield 60 for engagement with a roll 3| on the correspondingpawl II and the shield has an arm 82 connected to an operating rod, seeFig. 3. Each let-off has its own shield operating rod, the letofl's Fl,F2 and F3 having rods 83, 63 and 35, respectively, while the let-offsF4, F5 and F6 have similar rods 86, 61 and 68, respectively. Since thecontrol mechanism for the shields are the same on both sides of the loomI will describe only the mechanism at the right and shown in Fig. 2.

A fixed stud 10 affords support for three levers ".12 and 13 which areconnected, respectively,

to the rods 63, 34 and 65. These levers are the means by which thecorresponding shields are moved either to idle or shielding position.Thus, if lever 1| is rocked to the left as viewed in Fig. 2 its rod 33acting through arm 62 will move the shield 30 of let-oil Fl to theposition shown in Fig. 3 and permit the associated pawl to feed itsratchet wheel 40. If, on the other hand, lever 1! is moved to the rightas viewed in Fig. 2 the rod 33 will be moved rearwardly'to cause rockingof the shield 30 in a clockwise direction as viewed in Fig. 3 intoengagement with corresponding roll 6| to rock the associated pawl 4|around its axis and thereby move the pawl to inoperative position withrespect to the ratchet wheel 40. So long as the shield 30 is inshielding position due to rearward movement of lever 1| thecorresponding pawl will have idle strokes and the associated worm 36will remain at rest. When the shield is in idle or non-shieldingposition as shown in Fig. 3, however, each operating movement of thepawl will advance the ratchet wheel 40 and give the worm 33 a partialturn for the purpose of rotating the corresponding warp beam through itsworm wheel 35. While the detailed operation of the shield and pawl havebeen given with respect to the front let-off on the right hand side ofthe I loom, yet it is to be understood that each of the let-oil's willoperate in the same manner, levers 12 and 13 controlling the shields oflet-ofls F2 and F3, while the let-offsFl, F3 and F6 at the left handside of the loom have their shields similariy controlled by rods 66, 61and 68.

Each warp beam has its own whip roll and in the drawings I show-threewhip rolls DI, D2 and D3 for the beams RI, R2 and R3, and whip rolls D3,D5 and D6 for the beams Ll, L2 and L3 respectively. These whip rolls aresubstantially the same and each includes a 15 rotatable in bearings 18on the loom frame. The outer end of each shaft 15 has secured thereto aweight lever 11 which supports and is urged downwardly by a variableweight 80, as suggested in Fig.

Each shaft 15 is provided with several small forwardly, depending uponthe tension of the frame and then to the middle pair of rods 82,

corresponding sheet of warp. As shown in Fig. l the warp sheets from thefront pair of aligned beams RI and LI pass in front of a stationaryguide rod and thence upwardly to the rear of the back pair of rods 32and then forwardly to the harnesses H. In similar manner the warp sheetsfrom the middle beams R2 and L2 extend around guide rods 86, 81 and 88fixed to the loom while the sheets of warp from the back pair of beamsR3 and L3 pass around guides 90, 9| and 32 to the front whip rods 32.There are thus six relatively heavy shaft manner. I

In order that the position of each rod 82 may determine the position ofthe corresponding shield I use the mechanism shown in Figs. 1 and 2. Thefront right hand shaft I! has'secured thereto a collar I80 which ispivotally connected at III to the upper end of a rod I82 having securedthere-- to an adjustable collar I83. The lower end of rod I02 slidesthrough a swivel I pivotally mounted on arm I85 of lever 13. Acompression spring I06 extends between the collar II: and swivel I04 andexerts a downward force on arm I08 tending to move the lever 13forwardly, or in such direction as to move the rod 85 toward the frontof the loom and therefore keep the corresponding shield in idle ornon-shielding position. In similar manner the middle right hand rod IIis provided with the collar IIB connected to a rod III surrounded by aspring II2 which exerts a downward force on arm II3 of lever I2, and therear right hand shaft I8 carries a collar II! connected toa rod IIisurrounded by a spring II! which exerts a downward force on arm III oflever II. The forces exerted by the several springs can be adjusted bythe collars on the associated rods, and the position of the collars I00,I III and I II can be adjusted on the associated shafts 15 by means ofset screws I20. Similar mechanism at the left side of the loom isprovided for the shafts II corresponding to beams LI, L2 and L3.

The stopping mechanism for the loom includes an electric switch and acontroller therefor on each whip roll. The right hand side of the loomframe is provided with a small stand I25 on which are mounted threeelectric switches I28, I21 and I28, corresponding to beams RI, R2 andR3. Each switch has an arm I38 to operate a plunger I3I forming part ofthe switch. These switches are so placed on the support I25 that theirarms can be operated conveniently by their respective whip rolls andeach of the latter is provided with a collar I35 angularly adjustable onthe associated shaft I5 and having a projecting switch actuating armI36. Each arm I38 is capable of operating its corresponding arm I30 for,operation of the associated switch when the whip rolls rocks toward theleft as viewed in Fig. 2 to an abnormal position. Similar switches I31,I38 and I38 are provided for the whip rolls of beams LI, L2 and L3 atthe left hand side of the loom to be operated by arms I40 on theassociated whip rolls.

In operation, the warp beams will all have adequate supplies of warpwound thereon and then placed in the loom as suggested in Fig. 6. Thesheet of warp from each of the beams will be laid around the guidesalready described and over the appropriate bars 82 and thence forwardlyto the weaving instrumentalities. The weights 88 normally act to holdthe bars 82 rearwardly so that the arms I36 on the shafts ill will allbe either spaced from their associated switch operating arms I30, or atleast will be in such position as not to effect opening of the latterswitches. With each beat of the loom the rods 39 and will be movedforwardly to give all of the pawls II a working stroke, but under normalconditions the levers II, 12 and 13 will be turned to the left as viewedin Fig. 2 to place the shields in idle position and the pawls will beactive to turn their respective beams. Continued operation of the loomunder these conditions causes backward movement of the rods 82 andrearward movement of the shield controlling rods 83-. Eventually theshields III engage their rolls 8| and the pawls are temporarily disabledand stop feeding of the warp. The rods "then move for-' wardly incidentto consumption of warp and the shields start to move towardnon-shielding position. This alternate stopping and starting of theturning mechanism for the warp beams go on so long as all parts of theseveral let-off mechanisms function properly, but if one or another ofthe feeding mechanisms should fail to operate the corresponding beamwill remain at rest and its sheet of warp tightened sufiiciently to movethe associated whip roll bar 82 forwardly to an abnormal position. I Y

Fig; 8 shows diagrammatically the circuit and loom motor control usedwith my invention. Wires E and E represent the power lines, M the loomdriving motor appropriately connected to shaft II, and B the solenoidwhich when energized maintains the main loom switch I closed. The sixswitch units in Fig. 8 controlled by'the whip rolls are designated at 1'r and r, and 1 F and l and correspond to the beams RI, R2 and R3, andLI, L2 and 1.3, respectively.

When the loom operates as described the conditions shown in Fig. 8 willcontinue, and electric current will flow in the following circuit: wireE, switch I39 of the front left whip roll, wire ISO to the next switchin unit P, and then in succession through the switches I31, I28, I21.I28 of units 1 r 1' and 1", respectively, to solenoid S via wire Iii,and thence by wire I52 to power wire III, This circuit is kept closed solong as all the switches I28 are closed and results in energization ofsolenoid S to keep switch Illr closed. Current therefore flows from wireE, over wire I" to closed switch I", thence by wire I58 to motor M andthen back by wire I" to the opposite side E of the power source.

If any one of the warp sheets should become too tight and move its whiproll rod 82 to' abnormal forward position, the associated arm I38 willdepress its switch arm I30 and plunger ill to open the correspondingswitch I28, whereupon the flrst'traced circuit will be opened andsolenoid S will be deenergized. The resultant opening of switch I" willcause stoppage of the motor and the loom will come to rest. The weavercan then advance the ratchet wheel III of the tight warp sheetsufliciently to pay off enough warp to permit the associated rod 82 tomove rearwardly to its normal range of movement and effect closure ofits switch. Normal warp conditions will then have been established andweaving can be resumed, since switch I 48 will by this time be closed.

From the foregoing it will be seen that 'I have provided an electricallyoperating control for the loom which acts to stop the loom until a warpsheet becomes too tight. It will further be seen that I have provided aloom having a plurality of warp beams each associated with an electricswitch and wherein the switches are all connected electrically to meansfor controlling the loom motor in such a way that if any switch is openthe loom will be stopped. Also, I have provided a series circuitincluding a normally closed switch for each warp beam when its sheet ofwarp is under normal tension, abnormal tension in any sheet beingeffected to open the corresponding switch and thereby break the circuitso that the loom will be stopped.

Having thus described my invention it will be 4. h aseaaoo seen thatchanges and modifications may be 'made therein by those. skilled in theart withoutto stop, a sheet of warp subject to change from.

normal to excessive tension, an auxiliary electric switch controlled bysaid sheet 01. warp normally closed when warp tension is normal andopened by excessive tension of the warp, and electric circuit meanscontrolling the motor switch and controlled by said auxiliary switch andeffective when the auxiliary switch is closed to maintain said motorswitch closed and effective when said auxiliary switch is open to eflectopening oi said motor switch. h

2. In a loom having a driving motor and an electric motorswitchtherei'or which when closed causes the motor to operate and whenopen eflects stoppage ot the motor, a warp beam supplying a sheet ofwarp, a whip roll over which the sheet of warp passes, said whip rollbeing moved from normal to abnormal position by the warp sheet when thetension of the latter becomes excessive, normally closed electriccircuit means eflective only when closed to keep said motor switchclosed, said switch opening when the circuit means is opened, and meansoperated by the whip roll when the'latter moves to abnormal position toopen said circuit means to effect opening of the motor switch for thepurpose oi stopping the motor. I

3. In a loom having a driving motor and a master electric switchtherefor and an electromagnetic controller which when energizedmaintains said master switch closed to cause running of the motor butwhen deenergized etiects opening of the master switch to stop the motor,a warp beam having'a sheet of warp, a whip roll over which the sheet orwarp passes, means tending to maintain the whip roll in normal operatingposition, the sheet of warp when under excessive tension moving the whiproll to abnormal position against the action of said means, a normallyclosed auxiliary electric switch, an electric circuit including saidauxiliary switch and said electro-magnetic controller and normallyeffective to maintain the latter energized to hold the master switchclosed, and means moving with the whip roll when the latter moves sheetof warp moving from normal to abnormal position when the sheet of warpis under excessive-tension, and an auxiliary switch normally closed whenthe whip roll is in normal position, an electric circuit including saidsolenoid and auxiliary switch to maintain said solenoid energized tokeep the master switch closed when the auxiliary switch is closed, andmeans moved by the whip roll when the latter moves to abnormal positionto open the auxiliary switch and thereby break said circuit to effectdeenergizatlon of the solenoid and cause opening at the master switch tostop the motor.

5. In a loom having a plurality of warp beams each supplying a sheet orwarp, the loom having an electric driving motor and a motor switchoperated by an electro-magnetic controller e!- fecting. opening andclosing or the motor switch, a normally closed auxiliary electric switchfor each warp beam, an electric circuit including said auxiliaryswitches and controller in series and normally closed and causing thecontroller to maintain the motor switch closed to eflect running of themotor, said controller eflecting opening of the motor switch when saidcircuit is .broken, a whip roll for each warp beam movable from normalto abnormal position, and means on each whip roll operative when thelatter moves to abnormal position to open the associated auxiliaryswitch and break said circuit.

6. In a loom having a driving electric motor and a master electricswitch which when closed causes the motor to run and when open causesthe motor to stop. a pluralityof warp beams each controller and all theauxiliary switches and eifective only when closed to cause saidcontroller to keep the master switch closed, and means operative whenthe tension 01' any sheet of warp becomes excessive to open thecorresponding auxiliary switch and thereby break said series circuit.

'7. In a loom having a plurality of warp beams and a driving motor, amaster switchfor the motor, an electro-magnetic controller for themaster switch, a whip roll for each warp beam movable from normal toabnormal position, an auxiliary switch for each whip roll, an' operatoron each whip roll for the corresponding auxiliary switch, and meansconstituting an electric circuit including said auxiliary switches andelectro-magnetic controller normally effective to cause said-controllerto keep the master switch closed when all the whip rolls are in normalposition, operation of any auxiliary switch by the operator of thecorresponding whip roll eflfecting a change in said electric circuitmeans and altering the condition of the electro-magnetic controller forthe purpose of opening said master switch.

8. In a loom having a driving electric motor and a motor switch whichwhen closed causes the motor to run and when open causes the motor tostop, a warp beam from which extends a sheet of warp subject to changefrom normal,

to excessive tension, an auxiliary electric switch for said sheet ofwarp capable of being either in open or closed position, anelectromagnetic controller zfor the motor switch, and means constitutingan electric circuit including said auxiliary switch and saidelectromagnetic controller normally efiective when said auxiliary switchis in one of the positions thereof to cause the electromagneticcontroller to keep the motor switch closed when the sheet of warp isunder normal tension, occurrence of excessive tension in said sheet ofwarp causing the auxiliary switch to move to the other position thereofand effecting a change in said electric circuit means and altering thecondition of the electromagnetic controller for the purpose of efiectingopening said motor switch.

9. In a loom having a driving motor and a motor switch which when closedcauses the motor to run and when open causes the motor to stop, asheetof warp subject to change from normal to excessive tension, anelectromagnetic controller for the motor switch, an auxiliary switchcontrolled by the sheet of warp, and means constituting an electriccircuit including said electromagnetic controller and said auxiliaryswitch normally effective to cause said electromagnetic controller tokeep the motor switch closed when the tension of the sheet of warp isunder normal tension, operation of the auxiliary switch incident to achange in the warp sheet from normal to excessive tension effecting achange in said circuit means and altering the condition of theelectromagnetic controller for the purpose of effecting opening'saidmotor switch.

WALTER Y. ROBB.

